Method and device for protecting persons and/or products from air-borne particles

ABSTRACT

The invention relates to a method and a device for separating at least two physical areas ( 1, 2 ) and for reducing the transmission of air-borne particles between said physical areas so as to protect persons and/or products ( 26 ) from said air-borne particles. The persons is located at least partly in the first physical area ( 1 ) and the products ( 26 ) in the second physical area ( 2 ) and at least one flat jet ( 13 ) of purified air is used to separate the two areas. The invention is characterized in that at least one low-turbulence displacement air stream ( 14 ) of purified air is generated at least in the second physical area ( 2 ) near the at least one air jet ( 13 ) and said at least one displacement air stream is directed primarily in the same direction as the at least one air jet ( 13 ).

The invention relates to a method for separating at least two spatialareas and for reducing the transmission of airborne particles betweenthe spatial areas in order to protect persons and/or products from theairborne particles, the person being located at least in part in thefirst spatial area and the products in the second spatial area, and atleast one planar air jet of purified air being used for the separation.

The invention further relates to devices for carrying out the method.

Products within the meaning of this application are all articles,starting products, intermediate products and end products which are inany way handled, filled, tested or modified.

In many industries, for example in the manufacture of pharmaceuticalsand electronics components, either the product has to be protected fromairborne foreign particles or the persons involved in the operatingprocess have to be protected from airborne product particles. It is alsocommon for both protective functions, for product and persons, to haveto be provided.

Such devices (also called safety workbenches depending on their size anddesign) operating according to the laminar flow principle are known fromthe prior art, which devices, in order to protect personnel or products,permit only limited access to the product space. This principle isemployed, for example, in the HERAsafe® cytostatic safety workbenchesaccording to DIN 12980 and in the LaminAir® workbenches from the companyHeraeus Instruments GmbH, Hanau. Filtered air is delivered in the formof a vertical, low-turbulence displacement stream onto the top surfaceof the workbench and is suctioned off at the base in front of the rearwall of the workbench and at the front behind the front boundary of theworkbench. The front has a vertically displaceable protective screen.When the protective screen is fully or partly raised, outside air flowsinto the workbench through the access port of the workbench, and thisair is likewise suctioned off via the suction arrangements on the base.A disadvantage of these devices is that the narrow access into theproduct space greatly restricts the operator's freedom of movement.Maneuvers requiring greater freedom of movement than these devicespermit in the operating state cannot be performed in such devices unlessthe protective screen is raised above the correct operating position oris completely removed, as a consequence of which the protection ofpersons and products is no longer ensured to the full extent.

Devices operating according to the laminar flow principle are alsoknown, which devices do not spatially separate the product from thepersonnel. This principle is employed, for example, in the DispensingBooths from the company Extract Technology Limited, Huddersfield,England. Purified air is delivered, for example in the form of avertical, low-turbulence displacement stream, to the top of the boothand is suctioned off at the base area. A disadvantage of these devicesis that the product can only be handled well below the head level of thepersonnel if protection of the personnel from the product is to beguaranteed. A further disadvantage is that the product in these devicesis not adequately protected from foreign particles caused by thepersonnel.

Moreover, devices operating according to the laminar flow principle areknown in which only the product is protected, not the operatingpersonnel. This principle is employed, for example, in the horizontallaminar flow workbenches from the company Babcock-BSH, Bad Hersfeld,Germany. Purified air is delivered horizontally behind the product spacein the direction of the personnel. A disadvantage of these devices isthe total lack of protection of the personnel.

Devices operating according to the support jet principle are also knownwhich protect only the personnel. This principle is employed, forexample, in the WIBOjekt® work tables from the company GWE, Hude. Theoperating personnel pass their hands through a support jet which isdelivered via an ejector rail in the front area of the work table andgenerates a curtain of air between the head level of the operator andthe product space. Further support jets can also be directed from theceiling to the rear area of the work table. In this principle, thesuctioning arrangements are located in the rear area of the work table.The air capacity of the support jet is typically 1 to 10 liters persecond per meter of booth width. A disadvantage of these devices is thelack of product protection.

Against the background of this prior art, the object of the inventionwas to develop alternative methods and devices for protecting personsand products from airborne particles, and which methods and devices willnot have the disadvantage of significantly restricting the freedom ofmovement of the operating personnel.

According to the invention, this object is achieved by a method of thetype specified in the introduction, in which at least one low-turbulencedisplacement stream is generated with purified air near the at least oneair jet in at least the second spatial area, said at least onedisplacement stream being directed in essentially the same direction asthe at least one air jet.

The subject of the invention is therefore a method for separating atleast two spatial areas and for reducing the transmission of airborneparticles between the spatial areas in order to protect persons and/orproducts from the airborne particles, the person being located at leastin part in the first spatial area and the products in the second spatialarea, and at least one planar air jet of purified air being used for theseparation, wherein at least one low-turbulence displacement stream isgenerated with purified air near the at least one air jet in at leastthe second spatial area, said at least one displacement stream beingdirected in essentially the same direction as the at least one air jet.

A “low-turbulence displacement stream” within the meaning of theinvention is a stream in which a unidirectional air stream flows overthe whole cross section of a defined area with as far as possible auniform velocity and almost parallel flow lines (laminar flow). Thisdefinition is taken from the guidelines of the Verein deutscherIngeniouje (VDI) No. 2083 of December 1976, which are thus by referencea constituent part of the description.

A further subject of the invention is a device for carrying out thismethod, having one or more first means for generating one or more planarair jets, with which, in its intended use, at least one space is dividedinto at least a first spatial area and a second spatial area by means ofthe planar air jet or by means of each planar air jet, and productsbeing able to be arranged in the second spatial area, the device in thesecond spatial area having second means for generating a low-turbulencedisplacement stream.

Particular embodiments or designs are disclosed in the respectivesubclaims. It is also possible for one or more of the features disclosedin the subclaims, in combination with the features of the main claims,to represent inventive solutions to the object on which the invention isbased, and the features can also be combined in any desired way.

In a first preferred embodiment of the method according to theinvention, the displacement stream is guided at least partially at adistance of at most 0 to 50 cm from the at least one air jet. Adisplacement stream with an air velocity of 0.1 to 1.5 m/s, preferably0.2 to 0.6 m/s, especially preferably 0.3 to 0.45 m/s, is advantageouslygenerated, likewise at least one air jet with an air outlet velocity of2 to 30 m/s, preferably 3 to 10 m/s, especially preferably 5 to 8 m/s.In a further preferred embodiment, an air jet or a displacement streamis generated with an air outlet capacity of at least 10 li.N. (liters innorm) per second per meter breadth of the air jet transverse to thedirection of flow, preferably 10 to 300 li.N., especially preferably 20to 100 li.N., very especially preferably 40 to 80 li.N. At least thesecond spatial area can have zones which are not traversed by the airstream. In a further particular embodiment, at least the total airquantity of the at least one air jet and of the at least onedisplacement stream is suctioned off in at least one of the spatialareas. It is also advantageous for the air jet or each air jet to beoriented at a predetermined or selectable or adjustable angle, from therange of −45° to +45°, preferably −30° to +30°, especially preferably−15° to +15°, very especially preferably −5° to +5°, toward a lateralface of the displacement stream, relative to the direction of flow.

Preferred configurations of the device according to the invention forcarrying out the method can also be constructed accordingly.

In one preferred configuration of the device according to the invention,said device has one or more suction arrangements which are dimensionedsuch that altogether they can suction off at least the total airquantity of the air jets and of the displacement streams. The suctionarrangement or each suction arrangement is preferably arranged oppositethe first means for generating the air jets or the displacement flow.

The subject of the invention also includes a device for protectingpersons and/or products from airborne particles, having a partially openfront with a height of H [m] for access to the device, two side walls, arear wall, one or more means for blowing in filtered air, which meansare arranged on a side wall, and one or more suction devices, whereinthe blowing-in means are designed and arranged, on the one hand (4, 5),such that a planar air jet (13) with an air outlet capacity of in allmore than 10 li.N. per second and height H [m] can be guided from thearea of one side wall near the front to the other side wall in order toseparate the internal space (2) of the device from the surrounding area(1), and, on the other hand (3), such that, on that side of the air jet(13) facing away from the front, a purified, low-turbulence displacementstream (14) can be guided from one side wall to the other, and whereinthe suction devices (6) are arranged at least partially in the area ofthe device near the front and are dimensioned such that altogether theycan take up at least the total air quantity of the air jet (13) and ofthe displacement stream (14).

It is advantageous if the lateral suctioning extends over the entireheight H [unit meters] of the access cross section of the device.

It is advantageous for the air jet to be guided at a predetermined orselectable or adjustable angle, from the range of −45° to +45°,preferably −30° to +30°, especially preferably −15° to +15°, veryespecially preferably −5° to +5°, toward the front face of thedisplacement stream, relative to the direction of flow.

In a further configuration, the high air capacity of the support jet isachieved by combining a plurality of ejector rails one behind the other,preferably by 2 parallel ejector rails. The ejectors used can includeall ejector systems known to the skilled person, for example orifice orslit nozzles.

In a further particular configuration, the suctioning is obtained usingtwo parallel rows of orifices (suction rail) in a side wall at the frontboundary (front face) of the device.

In a further particular configuration, the air jet is inclined, at adefined, predetermined or selectable or adjustable angle, from the rangeof −30° to +30°, preferably −20° to +20°, especially preferably −10° to+10°, very especially preferably −5° to +5°, to the connection planebetween ejector rail and suction rail or to the horizontal.

In a further particular configuration, an air jet or a low-turbulencedisplacement stream with an air velocity of 0.1 to 1.5 m/s, preferably0.2 to 0.6 m/s, especially preferably 0.3 to 0.45 m/s, can be generated.

In a further particular configuration, the ejectors are suitable for anair outlet velocity of 2 to 30 m/s, preferably 3 to 10 m/s, especiallypreferably 5 to 8 m/s.

In a further particular configuration, the ejector rails are designedsuch that they can together generate an air outlet capacity of 10 to 300liters per second per meter height of that part of the front providedfor access, preferably 20 to 100 liters per second per meter height,especially preferably 40 to 80 liters per second per meter height.

This device according to the invention can in particular also becombined with one or more features from the other configurations.

The subject of the invention also includes a device for protectingpersons and/or products from airborne particles, having a partially openfront with a breadth of B [m] for access to the device, a top, a base, arear wall, one or more means for blowing in filtered air, which meansare arranged on the top, and one or more suction devices, wherein theblowing-in means are designed and arranged, on the one hand, such that aplanar air jet with an air outlet capacity of in all more than 10 li.N.per second and breadth B [m] can be guided downward from the area of thetop near the front in order to separate the internal space of the devicefrom the surrounding area, and, on the other hand, such that, on thatside of the air jet facing away from the front, a purified,low-turbulence displacement stream can be guided downward, and whereinthe suction devices are arranged at least partially in the area of thedevice near the front and are dimensioned such that altogether they cantake up at least the total air quantity of the air jet and of thedisplacement stream.

It is advantageous if the suctioning at the base extends over the entirebreadth B [unit meters] of the access cross section of the device.

The air jet and the displacement stream can likewise be guided from thebottom upward counter to the force of gravity. A corresponding deviceaccording to claim 23 is also the subject of the invention.

It is advantageous if the low-turbulence displacement stream can beguided at an angle which is inclined −20° to +20°, preferably −10° to+10°, especially preferably −5° to +5°, to the vertical.

In a further configuration, the high air capacity of the support jet isachieved by combining a plurality of ejector rails one behind the other,preferably by 2 parallel ejector rails. The ejectors used can includeall ejector systems known to the skilled person, for example orifice orslit nozzles.

In a further particular configuration, the suctioning is obtained usingtwo parallel rows of orifices (suction rail) in the base area at thefront boundary (front face) of the device.

It is advantageous if the air jet is inclined, at a defined,predetermined angle, from the range of −30° to +30°, preferably −20° to+20°, especially preferably −10° to +10°, very especially preferably −5°to +5°, to the connection plane between ejector rail and suction rail orto the vertical.

In a further particular configuration, a low-turbulence displacementstream with an air velocity of 0.1 to 1.5 m/s, preferably 0.2 to 0.6m/s, especially preferably 0.3 to 0.45 m/s, can be generated.

In a further particular configuration, the ejectors are suitable for anair outlet velocity of 2 to 30 m/s, preferably 3 to 10 m/s, especiallypreferably 5 to 8 m/s.

In a further particular configuration, the ejector rails are designedsuch that they can together generate an air outlet capacity of 10 to 300liters per second per meter breadth of that part of the front providedfor access, preferably 20 to 100 liters per second per meter breadth,especially preferably 40 to 80 liters per second per meter breadth, withwhich ranges from other combinations of said limits are also intended tobe disclosed.

The device according to the invention can also be combined in anydesired way with one or more features from the other configurations.

The invention is based on the surprising effect that the displacementstream stabilizes the planar air jet, so that the protective action ofthe combination of both is considerably better than expected.

It is especially surprising that, for example, the front boundary screenof a horizontal laminar flow work zone, which allows only limited accessto the product space, can be replaced by a broad support jet with highair capacity if the suctioning is largely limited to the area of thedevice near the front, and that then, despite the boundary screen beingremoved, both a high level of product protection and a high level ofpersonnel protection are guaranteed.

The advantages of the devices according to the invention are to be seenin the fact that while the operating personnel are allowed the greatestpossible freedom of movement, the protection of persons and productsfrom airborne particles is guaranteed.

The device according to the invention is explained in more detail on thebasis of a number of examples and with reference to FIGS. 1 to 5. Thisis not intended in any way to limit the scope of the invention.

FIG. 1 shows a diagrammatic representation of the method according tothe invention, using a device according to the invention representeddiagrammatically in cross section;

FIG. 2 shows a diagrammatic representation of a device and of a methodin accordance with Example 2;

FIG. 3 shows a diagrammatic representation of a device and of a methodin accordance with Counter Example 1;

FIG. 4a shows a diagrammatic representation of a first particularembodiment of the method and of the device in a plan view;

FIG. 4b shows a cross section through the device from FIG. 4a along theline A-B;

FIG. 4c shows a cross section of the device from FIG. 4a along the lineC-D;

FIG. 5 shows a diagrammatic representation of a second particularembodiment of the method and of the device in a lateral cross section.

EXAMPLE 1

A LaminAir® workbench, type HL 2472, with a protected product area(corresponds to the second spatial area) 2 and surrounding personnelarea 1 (corresponds to the first spatial area) is equipped at the topwith second means for generating a low-turbulence displacement stream14, namely with two-layer laminar flow generators 3 which are sealed offagainst the workbench walls except for a gap, the breadth of theworkbench and 8 mm deep, at a front screen 25. The diagramaticallyillustrated screen 25 of the workbench is raised as far as the loweredge of the laminar flow generators. Arranged at the height of the loweredge of the laminar flow generators, directly from outside on the raisedworkbench screen, there are first means 4, 5 for generating a planar airjet 13, namely an ejector rail 4 the breadth of the workbench, and a gap5 with downward air outlet. The ejector 4 is equipped with a combinationof orifice and slit nozzles with an effective cross section of 0.9 mm.The resulting gap 5 between laminar flow generators 3 and raised screenserves as an 8-mm wide ejector 5 with downwardly directed air outlet.

The base of the workbench is sealed off except for the suction openings6 on the open screen. The laminar flow generators 3 are in this exampleoperated at an air outlet velocity of about 0.45 m/s.

Ejector 4 in this example is operated at an air outlet velocity of 5m/s. Ejector 5 in this example is operated at an air outlet velocity of7 m/s. The planar air jet 13, which is generated by the two ejectors 4,5, consequently has an air outlet capacity of 46 li.N. per second andmeter breadth of the air jet 13. The air distribution in the workbenchis shown diagrammatically in FIG. 1 in cross section. The arrows 14below the laminar flow generators 3 indicate the low-turbulencedisplacement stream of uniform velocity and with parallel flow lines.

Protection factors are determined below by measurements. The protectionfactor is defined as the ratio of the dust content between “uncleanside” and “clean side” when a dust source is provided on the uncleanside. The device therefore gives better protection, the higher theprotection factor.

For personnel protection, the workbench center 5 cm in front of theworkbench opening (personnel area 1) is regarded as the clean side, andthe workbench interior behind the suction arrangement (product area 2)is regarded as the unclean side. For assessing product protection, theunclean and clean sides are correspondingly reversed.

The protection factor is the ratio of the quantity of air borneparticles in a contaminated area to the quantity of particles in aprotected area. The protection factor for personnel protection is400,000 when the workbench is in the rest state, i.e. withoutintervention by the operator. With simulated work movements, i.e. movingthe hands in and out, and other movements of both arms in the booth, avalue of 750 is obtained for personnel protection.

The protection factor for product protection is 160 million when theworkbench is in the rest state, i.e. without intervention by theoperator. With simulated work movements, i.e. moving the hands in andout, and other movements of both arms in the booth, a value of 6,000 isobtained for product protection.

EXAMPLE 2

A workbench is constructed and operated as in Example 1. In contrast toExample 1, however, the gap between laminar flow generators 3 and raisedscreen is sealed off, so that no air escapes from ejector 5. Ejector 4is operated, as in Example 1, at an air outlet velocity of 5 m/s. Theplanar air jet consequently has an air outlet capacity of 6.3 li.N. persecond and meter breadth of the air jet. The air distribution in thework bench is shown diagrammatically in cross section in FIG. 2 below.

The protection factor for personnel protection is now 300 when theworkbench is in the rest state, i.e. without intervention by theoperator. With simulated work movements, i.e. moving the hands in andout, and other movements of both arms in the booth, a value of 30 isobtained for personnel protection.

The protection factor for product protection is now 50 million when theworkbench is in the rest state, i.e. without intervention by theoperator. With simulated work movements, i.e. moving the hands in andout, and other movements of both arms in the booth, a value of 40 isobtained for product protection.

COUNTER EXAMPLE 1

A workbench is constructed and operated as in Example 1. In contrast toExample 1, however, the gap between laminar flow generators 3 and raisedscreen is sealed off, so that no air escapes from ejector 5. Ejector 4is also not operated, so that no air escapes from it either. The airdistribution in the work bench is shown diagrammatically in crosssection in FIG. 3.

The protection factor for personnel protection is now 20 when theworkbench is in the rest state, i.e. without intervention by theoperator. With simulated work movements, i.e. moving the hands in andout, and other movements of both arms in the booth, a value of 10 isobtained for personnel protection.

The protection factor for product protection is now 6000 when theworkbench is in the rest state, i.e. without intervention by theoperator. With simulated work movements, i.e. moving the hands in andout, and other movements of both arms in the booth, a value of 30 isobtained for product protection.

EXAMPLE 3

A device for combined product protection and personnel protection ismade up of an air delivery element 19 and an air suction element 20, asshown diagramatically in FIGS. 4a and 4 b. Both elements stand in a room(not shown) with separate clean air supply system and exhaust systemwith integrated air cleaning (not shown). The open and at the same timeprotected product area 2 in which dust-producing products can be handledopenly is situated in this device between the air delivery element 19and the air suction element 20, as shown in FIG. 4c. The protectedpersonnel area 1 is located in the entire spatial area surrounding theprotected product area.

The air delivery element 19 consists essentially of an air admissionpipe 7, into which purified air is fed from the delivery system, adistributor 8, a downwardly angled air delivery segment 22, and anupright segment 9. The air delivery segment 22 conveys the air deliveredvia the distributor on the one hand via a rectangular laminar flowgenerator 10 and on the other hand via four ejector rails 11, whichenclose the laminar flow generator 10, in the direction of the suctionelement 20. The air velocity of the air delivered by the laminar flowgenerator 10 is 0.45 m/s in this example. The air outlet velocity fromthe ejector rails is 5 m/s in this example. The resulting airdistribution at the air delivery element 19 is likewise showndiagrammatically in FIGS. 4a and 4 b.

The air suction element 20 has two suction rails 12 via which 1.4 timesthe air quantity delivered by the air delivery element can be suctionedoff and conveyed to the extraction system.

EXAMPLE 4

A mobile device for the combined protection of personnel and productsprotection is shown diagramatically in cross section in FIG. 5. Thedevice has a protected product area 2 which is open both to the sidesand also in the upper front area. The protected personnel area 1comprises the area surrounding the device. Side openings can be used tosupply the product area with product containers, whereas the frontopening gives the person shown free access for protected handling ofproducts 26.

Situated in the front ceiling area of the device there are two parallelejector rails via which a planar air jet 13 can be delivered downward atan angle of about 100 to the vertical front face of the device. Behindthese in the ceiling/ area there are laminar flow generators which canform a downward low-turbulence displacement stream 14. The delivered airis taken up, on the one hand, in the front area of the device, via anexhaust air channel 18 which is provided at the top with suctionopenings, and, on the other hand, in the lower rear area of the productarea, at the base of the device and fed to a filter 16 via a fan 15.Some of the purified air flowing from the filter serves as intake air 21for the laminar flow generator and the ejector rails and some of it isdischarged as exhaust air 17.

What is claimed is:
 1. A method for separating at least two spatialareas (1, 2) and for reducing the transmission of airborne particlesbetween the spatial areas (1, 2) in order to protect persons and/orproducts (26) from the airborne particles, the person being located atleast in part in the first spatial area (1) and the products in thesecond spatial area (2), and at least one planar air jet (13) ofpurified air being used for the separation, in which at least onelow-turbulence displacement stream (14) is generated with purified airnear the at least one air jet (13) in at least the second spatial area(2), said at least one displacement stream (14) being directed inessentially the same direction as the at least one air jet (13), whereinat least two planar air jets (13) with an air outlet velocity of 2 to 30m/s are generated for the separation.
 2. The method as claimed in claim1, in which the displacement stream (14) is guided at least partially ata distance of at most 0 to 50 cm from the at least one air jet (13). 3.The method as claimed in claim 1, in which at least one displacementstream (14) with an air velocity of 0.1 to 1.5 m/s is generated.
 4. Themethod as claimed in claim 1, in which an air jet (13) or a displacementstream (14) is generated with an air outlet capacity of at least 10li.N. per second per meter breadth of the air jet (13) transverse to thedirection of flow.
 5. The method as claimed in claim 1, in which atleast the second spatial area (2) has untraversed zones.
 6. The methodas claimed in claim 1, in which at least the total air quantity of theat least one air jet (13) and of the at least one displacement stream(14) is suctioned off in at least one of the spatial areas (1,2).
 7. Themethod as claimed in claim 1, in which the air jet or each air jet (13)is oriented at an angle, from the range of −45° to +45° toward a lateralface of the displacement stream (14), relative to the direction of flow.8. A device for carrying out the method as claimed in claim 1, havingone or more first means (4, 5) for generating one or more planar airjets (13), with which, in its intended use, at least one space isdivided into at least a first spatial area (1) and a second spatial area(2) by means of the planar air jet or by means of each planar air jet(13), and products (26) being able to be arranged in the second spatialarea (2), the device in the second spatial area (2) having second means(3) for generating a low-turbulence displacement stream (14).
 9. Thedevice as claimed in claim 8, in which the device has one or moresuction arrangements (6, 15) which are dimensioned such that altogetherthey can suction off at least the total air quantity of the air jets(13) and of the displacement streams (14).
 10. The device as claimed inclaim 9, in which the suction arrangement or each suction arrangement(6, 15) is arranged opposite the first means (4, 5) for generating theair jets (13) or the displacement flow (14).
 11. The method as claimedin claim 8, which the second means (3) are arranged and designed suchthat the displacement stream (14) can be guided at least partially at adistance of at most 0 to 50 cm from the least one air jet (13).
 12. Thedevice as claimed in claim 8, in which the second means (3) are designedsuch that a displacement stream (14) with an air velocity of 0.1 to 1.5m/s can be generated.
 13. The device as claimed in claim 8, in which thefirst means (4, 5) are designed such that an air jet (13) with an airoutlet velocity of 2 to 30 m/s can be generated.
 14. The device asclaimed in claim 8, in which the means (4,5) for generating the air jets(13) are dimensioned such that planar air jets with an air outletcapacity of at least 10 li.N. per second and breadth B of the planar airjet can be generated.
 15. The device as claimed in claim 8, in which themeans (4, 5) for generating the air jet (13) or each air jet arearranged and oriented such that the air jet or each air jet (13) can beoriented at an angle, from the range of −45° to +45° toward a lateralface of the displacement stream (14), relative to the direction of flow.16. The device as claimed in claim 8, in which the means (4, 5) forgenerating the air jet or each air jet (13) are designed as ejectorrails.
 17. The device as claimed in claim 16, in which at least twoejector rails are arranged in parallel.
 18. A device for implementingthe method as claimed in claim 1, having a partially open front with aheight of H for access to the device, two side walls, a rear wall, oneor more means for blowing in filtered air, which means are arranged on aside wall, and one or more suction devices, wherein the blowing-in meansare designed and arranged, on the one hand, such that at least twoplanar air jets with an air outlet velocity of 2 to 30 m/s and with anair outlet capacity in each case of in all more than 10 li.N. per secondand height H can be guided from the area of one side wall near the frontto the other side wall in order to separate the internal space of thedevice from the surrounding area, and, on the other hand, such that, onthat side of the air jets facing away from the front, a purified,low-turbulence displacement stream can be guided from one side wall tothe other, and wherein the suction devices are arranged at leastpartially in the area of the device near the front and are dimensionedsuch that altogether they can take up at least the total air quantity ofthe air jets and of the displacement stream.
 19. The device as claimedin claim 18, wherein the air jets can be guided at a predetermined orselectable or adjustable angle, from the arrange of −45° to +45° towardthe front face of the displacement stream, relative to the direction offlow.
 20. The device as claimed in claim 18, wherein the air outletcapacity is 10 to 300 li.N. per second per meter height of that part ofthe front provided for access.
 21. A device for implementing the methodas claimed in claim 1, having a partially open front with a breadth of Bfor access to the device, a top, a base, a rear wall, one or more meansfor blowing in filtered air, which means are arranged on the top, andone for more suction devices, wherein the blowing in means are designedand arranged, on the one hand (4, 5), such that at least two planar airjets with an air outlet velocity of 2 to 30 m/s and with an air outletcapacity in each case of in all more than 10 li.N. per second andbreadth B can be guided downward from the area of the top near the frontin order to separate the internal space (2) of the device from thesurrounding area (1), and, on the other hand (3), such that, on thatside of the air jet (13) facing away from the front, a purified,low-turbulence displacement stream (14) can be guided downward, andwherein the suction devices (6) are arranged at least partially in thearea of the device near the front and are dimensioned such thataltogether they can take up at least the total air quantity of the airjets (13) and of the displacement stream (14).
 22. A device forimplementing the method as claimed in claim 1, having a partially openfront with a breadth of B for access to the device, a bottom, a top, abase, a rear wall, one or more means for blowing in filtered air, whichmeans are arranged on the bottom, and one or more suction devices,wherein the blowing-in means are designed and arranged, on the one hand,such that at least two planar air jets with an air outlet velocity of 2to 30 m/s and with an air outlet capacity in each case of in all morethan 10 li.N. per second and breadth B can be guided upward from thearea of the bottom near the front in order to separate the internalspace from the device on the surrounding area, and, on the other hand,such that, on that side of the air jet facing away from the front, apurified, low-turbulence displacement stream can be guided upward, andwherein the suction devices are arranged at least partially in the areaof the device near the front and are dimensioned such that altogetherthey can take up at least the total air quantity of the air jets and ofthe displacement stream.
 23. The device as claimed in claim 21, whereinthe air jet can be guided at an angle, from the range of −45° to +45°toward the front face of the displacement stream, relative to thedirection of flow.
 24. The device as claimed in claim 21, wherein theair outlet capacity is 10 to 300 liters per second per meter breadth ofthat part of the front provided for access.
 25. The device as claimed inclaim 18, in which the device has a displaceable screen (25) on thefront.